In April 2025, California Governor Gavin Newsom initiated legal proceedings against the Trump administration, contesting the President's authority to impose extensive tariffs on imports from nations including Mexico, Canada, and China. Filed in the U.S. District Court for the Northern District of California, the lawsuit argues that President Trump's invocation of the International Emergency Economic Powers Act (IEEPA) to levy a 10% tariff on all imports exceeds the powers granted by the act, which is intended to address foreign threats through measures like freezing or blocking transactions, not imposing tariffs. ​

Governor Newsom emphasized that these tariffs could severely impact California's economy, the largest in the United States and a significant hub for international trade. He stated, "We're standing up for American families who can't afford to let the chaos continue," highlighting concerns over potential job losses and economic instability resulting from the tariffs.

In response, the White House defended the tariff strategy, asserting that it is a necessary measure to address persistent trade deficits and protect American industries. A spokesperson criticized the lawsuit, suggesting that state leaders should focus on local issues rather than challenging federal trade policies.